What the fee is
When you create a Google Play developer account, Google charges a one-time 25$ registration fee. It's paid once, directly to Google, and never renews — a key difference from Apple's 99$/year. The fee covers unlimited app publishing under your account.
One-time vs Apple's yearly fee
The real total cost
For a free app, the 25$ is the only cost Google charges. The other variable is how you build the signed .aab: hand-coding it is free but technical; a service like SaaSToStore builds it from your URL with a free first build and paid plans from 9€. So a published Android app can cost as little as 25$ plus a one-time build.